Opioid Overdose: Limitations in Naloxone Reversal of Respiratory Depression and Prevention of Cardiac Arrest.

Opioids are effective analgesics, but they can have harmful adverse effects, such as addiction and potentially fatal respiratory depression. Naloxone is currently the only available treatment for reversing the negative effects of opioids, including respiratory depression. However, the effectiveness of naloxone, particularly after an opioid overdose, varies depending on the pharmacokinetics and the pharmacodynamics of the opioid that was overdosed. Long-acting opioids, and those with a high affinity at the µ-opioid receptor and/or slow receptor dissociation kinetics, are particularly resistant to the effects of naloxone. In this review, the authors examine the pharmacology of naloxone and its safety and limitations in reversing opioid-induced respiratory depression under different circumstances, including its ability to prevent cardiac arrest.

Advances in Reversal Strategies of Opioid-induced Respiratory Toxicity.

Opioids may produce life-threatening respiratory depression and death from their actions at the opioid receptors within the brainstem respiratory neuronal network. Since there is an increasing number of conditions where the administration of the opioid receptor antagonist naloxone is inadequate or undesired, there is an increased interest in the development of novel reversal and prevention strategies aimed at providing efficacy close to that of the opioid receptor antagonist naloxone but with fewer of its drawbacks such as its short duration of action and lesser ability to reverse high-affinity opioids, such as carfentanil, or drug combinations. To give an overview of this highly relevant topic, the authors systematically discuss predominantly experimental pharmacotherapies, published in the last 5 yr, aimed at reversal of opioid-induced respiratory depression as alternatives to naloxone. The respiratory stimulants are discussed based on their characteristics and mechanism of action: nonopioid controlled substances (e.g., amphetamine, cannabinoids, ketamine), hormones (thyrotropin releasing hormone, oxytocin), nicotinic acetylcholine receptor agonists, ampakines, serotonin receptor agonists, antioxidants, miscellaneous peptides, potassium channel blockers acting at the carotid bodies (doxapram, ENA001), sequestration techniques (scrubber molecules, immunopharmacotherapy), and opioids (partial agonists/antagonists). The authors argue that none of these often still experimental therapies are sufficiently tested with respect to efficacy and safety, and many of the agents presented have a lesser efficacy at deeper levels of respiratory depression, i.e., inability to overcome apnea, or have ample side effects. The authors suggest development of reversal strategies that combine respiratory stimulants with naloxone. Furthermore, they encourage collaborations between research groups to expedite development of viable reversal strategies of potent synthetic opioid-induced respiratory depression.

Insights into the Use of Peripherally Acting µ-Opioid Receptor Antagonists (PAMORAs) in Oncologic Patients: from Scientific Evidence to Real Clinical Practice.

OPINION STATEMENT: Management of chronic pain is crucial to improve the quality of life of cancer and palliative care patients. Opioid-based treatments used to control pain can be prolonged over time. Unfortunately, constipation is one of the most disturbing adverse effects of long-term use of opioids. Opioid-induced constipation (OIC) occurs when opioids bind to the specific receptors present in the gastrointestinal (GI) tract, and can affect any patients receiving chronic opioid therapy, including cancer patients. The limited efficacy of laxatives to treat OIC symptoms prompted the search for new therapeutic strategies. Peripherally acting µ-opioid receptor antagonists (PAMORAs) have recently emerged as new effective drugs for OIC management due to their specific binding to enteric µ-receptors. Little information is available on the use of PAMORAs in real-life practice for OIC treatment in cancer patients. In this paper, a panel of experts specializing in cancer and palliative care pools their clinical experience with PAMORAs in cancer patients presenting OIC and highlights the importance of timing and choice of therapy in achieving prompt OIC management and benefitting patients.

A Literature Review Examining Primary Outcomes of Medication Treatment Studies for Opioid Use Disorder: What Outcome Should Be Used to Measure Opioid Treatment Success?

BACKGROUND AND OBJECTIVES: Medications for opioid use disorder (MOUD) reduce opioid use and overdose; however, MOUD clinical trials have used varying primary outcomes to document treatment success. We conducted a literature review to assess and critically examine the methodologies used in MOUD treatment studies. METHODS: Published studies in English that examined MOUD (buprenorphine, methadone, or extended-release naltrexone) were included (N = 20). The methods and frequencies of measuring primary opioid outcomes, including urine drug tests (UDTs) and self-report of opioid use were compared among studies. RESULTS: A total of 20 studies fit the inclusion criteria. Each study assessed opioid use; only 12 had opioid use as a primary outcome. Other primary outcomes included retention in treatment (N = 6), and two had other primary outcomes (death and opioid withdrawal symptoms). Opioid use was assessed through both self-report and UDTs in 15 studies. Two studies did not use UDTs. Differences were found in the methods used for how opioid use, retention in treatment, self-report of opioid use, and UDTs were measured. DISCUSSION AND CONCLUSIONS: The different primary outcomes used and operational definitions in each study make comparisons between studies difficult. The use of both self-report and UDTs for opioid use has several advantages, and if possible, researchers should use both measures. SCIENTIFIC SIGNIFICANCE: This is the first review critically examining outcome measures from MOUD treatment studies. Creating a standard for opioid treatment outcomes in MOUD studies will allow for generalizable results that can inform both researchers and clinicians to better care for those with OUD. (Am J Addict 2020;00:00-00).

Dancing with Deterrents: Understanding the Role of Abuse-Deterrent Opioid Formulations and Naloxone in Managing Cancer Pain.

Prescription opioids are commonly prescribed for the relief of many kinds of pain syndromes, including cancer pain. In order to combat the growing rates of abuse and misuse of prescription opioids, the Centers for Disease Control and Prevention, along with the U.S. Food and Drug Administration and multiple pharmaceutical companies, have implemented many risk mitigation strategies. Abuse-deterrent drug delivery technology and more consistent prescribing of the opioid antagonist, naloxone, are two of the mechanisms of reducing harm in patients on chronic opioid therapy. Abuse-deterrent technology is implemented into different commercially available opioid products with the intent of discouraging manipulation of the opioid or making the use of the manipulated opioid less appealing. Use of the opioid antagonist, naloxone, for reversal of intentional or unintentional opioid overdose is a safe and effective means to reduce potential risk in patients who are on opioids for pain management. These mechanisms have multiple advantages and limitations that influence their practical use specifically in patients with cancer pain. Patients with cancer pain have unique therapeutic needs and goals, and their balance of treatment risks and benefits differs from that of other kinds of chronic pain disorders. This article provides an overview of the advantages and limitations of these specific harm-reduction strategies and provides guidance on how to practically utilize them when caring for patients with cancer pain. IMPLICATIONS FOR PRACTICE: Treating cancer pain has important and unique considerations compared with other chronic, noncancer pain disorders. The use of risk mitigation strategies for opioid prescribing as promoted by the Centers for Disease Control and Prevention does not translate seamlessly to patients with cancer. It is crucial to be wary of the advantages and pitfalls of all risk mitigation strategies related to opioid use in patients with cancer pain. Careful examination of patient-specific risks and benefits should always be considered when implementing pharmacologic treatment and harm-reduction strategies for the management of cancer pain.

The Effect of Buprenorphine on Methamphetamine Cravings.

BACKGROUND: Methamphetamine (METH) abuse and dependence present a major global problem. We investigated the efficacy of adding buprenorphine in reducing METH cravings during treatment with the Matrix program. METHODS: This was a randomized, double-blind, controlled clinical trial of 40 men between the age of 18 and 40 years who were referred to the addiction treatment center at Noor Hospital from December 2012 to September 2013. All of the selected subjects participated in the Matrix program and were randomly assigned into 2 groups and given either buprenorphine or a placebo. A 4-month intervention program with buprenorphine or a placebo was arranged for each group. Demographic variables of the 2 groups, descriptive indices from the cocaine craving questionnaire-brief (CCQ-Brief), the ratio of urine tests positive for METH, and the frequency of drug complications were regularly evaluated in both groups every 2 weeks and, if not possible, by the third or fourth week. All analyses were performed by SPSS20 using analysis of covariance, χ, and t tests. RESULTS: The average of indices from the cocaine craving questionnaire-brief score, except the 2 initial measurements, was significantly lower in the intervention group in all measurements (P < 0.05). Apart from weeks 3 and 28, the ratio of positive tests was significantly different in all measurements in both groups (P < 0.05). CONCLUSIONS: Buprenorphine augmentation, in comparison with the placebo, significantly reduced the craving to use METH during treatment with the Matrix program.

Nicotine effects and the endogenous opioid system.

Nicotine (NIC) is an exogenous ligand of the nicotinic acetylcholine receptor (nAChR), and it influences various functions in the central nervous system. Systemic administration of NIC elicits the release of endogenous opioids (endorphins, enkephalins, and dynorphins) in the supraspinal cord. Additionally, systemic NIC administration induces the release of methionine-enkephalin in the spinal dorsal horn. NIC has acute neurophysiological actions, including antinociceptive effects, and the ability to activate the hypothalamic-pituitary-adrenal (HPA) axis. The endogenous opioid system participates in NIC-induced antinociception, but not HPA axis activation. Moreover, NIC-induced antinociception is mediated by α4ß2 and α7 nAChRs, while NIC-induced HPA axis activation is mediated by α4ß2, not α7, suggesting that the effects of NIC on the endogenous opioid system are mediated by α7, not α4ß2. NIC has substantial physical dependence liability. The opioid-receptor antagonist naloxone (NLX) elicits NIC withdrawal after repeated NIC administration, and NLX-induced NIC withdrawal is inhibited by concomitant administration of an opioid-receptor antagonist. NLX-induced NIC withdrawal is also inhibited by concomitant administration of an α7 antagonist, but not an α4ß2 antagonist. Taken together, these findings suggest that NIC-induced antinociception and the development of physical dependence are mediated by the endogenous opioid system, via the α7 nAChR.

[Therapy in heroin addiction]. / A heroinaddikció gyógyítása.

Heroin addiction is one of the most devastating and expensive of public health problems. The most effective treatment is opioid replacement therapy. Replacement of heroin, a short-acting euphoriant with methadone or other opioids that have significantly longer duration of action provides a number of therapeutic benefits. Opioid detoxification has a role in both preventing acute withdrawal and maintaining long-term abstinence. Opioid-based detoxification is based on the principle of cross-tolerance, in which one opioid is replaced with another one that is slowly tapered. For the treatment of heroin addicts a wide range of psychosocial and pharmacotherapeutic treatments are available; of these, methadone maintenance therapy has the most evidence of benefit. Methadone maintenance reduces and/or eliminates the use of heroin, reduces the death rate and criminality associated with heroin use, and allows patients to improve their health and social productivity. In addition, enrollment in methadone maintenance has the potential to reduce the transmission of infectious diseases associated with heroin injection, such as hepatitis and HIV. The principal effects of methadone maintenance are to relieve narcotic craving, suppress the abstinence syndrome, and block the euphoric effects associated with heroin. There is growing interest in expanding treatment into primary care, allowing opioid addiction to be managed like other chronic illnesses. Buprenorphine which is a long-acting partial agonist was also approved as pharmacotherapy for opioid dependence. Opioid antagonists can reduce heroin self-administration and opioid craving in detoxified addicts. Naltrexone, which is a long-acting competitive antagonist at the opioid receptors, blocks the subjective and objective responses produced by intravenous opioids. Naltrexone is employed to accelerate opioid detoxification by displacing heroin and as a maintenance agent for detoxified formerly heroin-dependent patients who want to remain opioid-free.

[Agonists of opioid receptors may aggravate ischemic and reperfusion damages of the heart].

Authors analyzed articles that opioids may aggravate ischemic and reperfusion damages of the heart but the opioid receptor antagonists may prevent these damages. Authors concluded the it is existed opioid receptor pool an activation of its decreases cardiac tolerance to an impact of ischemia-reperfusion.

Buprenorphine in Neonatal Abstinence Syndrome.

Infants exposed in utero to opioids will demonstrate a withdrawal syndrome known as neonatal abstinence syndrome (NAS). Buprenorphine is a long-acting opioid with therapeutic use in medication-assisted treatment of opioid dependency in adults and adolescents. Emerging data from clinical trials and treatment cohorts demonstrate the efficacy and safety of sublingual buprenorphine for those infants with NAS who require pharmacologic treatment. Pharmacometric modeling will assist in defining the exposure-response relationships and facilitate dose optimization.

CE: Acute Pain Management for People with Opioid Use Disorder.

: Medication-assisted treatment for opioid use disorder (OUD), which incorporates methadone, buprenorphine, or naltrexone, has been shown to reduce all-cause mortality rates in patients with this disease-and the numbers of patients receiving such treatment is substantial. In 2016, among U.S. patients with OUD, nearly 350,000 were treated with methadone, more than 60,000 were treated with buprenorphine, and more than 10,000 were treated with naltrexone. Managing acute pain in patients receiving this treatment can be a significant nursing challenge. The authors discuss the attributes of the three medications used to treat OUD and, through a composite patient case, review how to manage acute pain effectively in patients receiving this type of treatment.This article is one in a series on palliative care developed in collaboration with the Hospice and Palliative Nurses Association (https://advancingexpertcare.org), which offers education, certification, advocacy, leadership, and research on palliative care.

Understanding how opioids contribute to reward and analgesia.

Opioids acting at the mu opioid (MOP) receptor produce powerful analgesia. They also produce an intensely rewarding effect that can lead to addiction. The analgesic effect of MOP receptor agonists derives from a direct inhibitory effect on pain transmission at the spinal-cord level and through activation of a descending pain-modulatory pathway. The rewarding effect of MOP agonists is the result of their actions in the mesostriatal dopamine pathway classically associated with both natural and drug rewards. Both the analgesic and rewarding effect of MOP agonists are best understood in the context of decision making under conditions of conflict. Pain is one of many competing motivational states, and endogenous opioids suppress responses to noxious stimuli in the presence of conflicting motivations, such as hunger or a threatening predator. When a food reward is available, MOP agonists microinjected into the mesostriatal circuit promote its consumption, while concomitantly suppressing responses to noxious stimulation. The mesostriatal "reward" circuit, thus, appears to perform a function critical to decision making and can either amplify or suppress responses to noxious stimuli.

Novel opioid antagonists for opioid-induced bowel dysfunction and postoperative ileus.

Methylnaltrexone and alvimopan are two new and potentially useful agents in the management of opioid-induced bowel dysfunction and prevention of postoperative ileus. Both agents have promising prokinetic properties and appear to be capable of reversing the effects of opioids on delayed gastrointestinal transit. This article reviews currently available published literature to provide an overview of the clinical trials and to provide insight for the potential use of these agents for patients requiring opioid based analgesia. These compounds represent a new class of compounds that may impact the therapeutics for opioid induced bowel dysfunction as well as postoperative ileus.

Reducing the harm of opioid overdose with the safe use of naloxone : a pharmacologic review.

INTRODUCTION: Opioid overdose fatality has increased threefold since 1999. As a result, prescription drug overdose surpassed motor vehicle collision as the leading cause of unintentional injury-related death in the USA. Naloxone , an opioid antagonist that has been available for decades, can safely reverse opioid overdose if used promptly and correctly. However, clinicians often overestimate the dose of naloxone needed to achieve the desired clinical outcome, precipitating acute opioid withdrawal syndrome (OWS). AREAS COVERED: This article provides a comprehensive review of naloxone's pharmacologic properties and its clinical application to promote the safe use of naloxone in acute management of opioid intoxication and to mitigate the risk of precipitated OWS. Available clinical data on opioid-receptor kinetics that influence the reversal of opioid agonism by naloxone are discussed. Additionally, the legal and social barriers to take home naloxone programs are addressed. EXPERT OPINION: Naloxone is an intrinsically safe drug, and may be administered in large doses with minimal clinical effect in non-opioid-dependent patients. However, when administered to opioid-dependent patients, naloxone can result in acute opioid withdrawal. Therefore, it is prudent to use low-dose naloxone (0.04 mg) with appropriate titration to reverse ventilatory depression in this population.

Buprenorphine: a primer for emergency physicians.

The recent approval of office-based treatment for opioid addiction and US Food and Drug Administration approval of buprenorphine will expand treatment options for opioid addiction. Buprenorphine is classified as a partial micro opioid agonist and a weak kappa antagonist. It has a high affinity for the micro receptor, with slow dissociation resulting in a long duration of action and an analgesic potency 25 to 40 times more potent than morphine. At higher doses, its agonist effects plateau and it begins to behave more like an antagonist, limiting the maximal analgesic effect and respiratory depression. This "ceiling effect" confers a high safety profile clinically, a low level of physical dependence, and only mild withdrawal symptoms on cessation after prolonged administration. Suboxone contains a mixture of buprenorphine and naloxone. The naloxone is poorly absorbed sublingually and is designed to discourage intravenous use. Subutex, buprenorphine only, will also be available primarily as an initial test dose. Clinicians will be using this drug for detoxification or for maintenance of opioid addiction. Patients with recent illicit opioid use may develop a mild precipitated withdrawal syndrome with the induction of buprenorphine. Acute buprenorphine intoxication may present with some diffuse mild mental status changes, mild to minimal respiratory depression, small but not pinpoint pupils, and relatively normal vital signs. Naloxone may improve respiratory depression but will have limited effect on other symptoms. Patients with significant symptoms related to buprenorphine should be admitted to the hospital for observation because symptoms will persist for 12 to 24 hours.

Neuroendocrine and behavioural responses to opioid receptor-antagonist during heroin detoxification: relationship with personality traits.

The present study investigated clinical, cardiovascular and neuroendocrine consequences of rapid opioid detoxification (ROD) in heroin-dependent individuals, affected, or not, by comorbid antisocial personality disorder (ASPD). Thirty-two patients underwent ROD and subsequent treatment with daily naltrexone: 3 days detoxification procedures were performed utilizing clonidine, baclofen, oxazepam and ketoprofene, without anaesthesia. Withdrawal symptoms, mood changes, cardiovascular indexes (heart rate, blood pressure), norepinephrine (NE), epinephrine (EPI), adrenocorticotropic hormone (ACTH) and cortisol (CORT) were evaluated during naloxone-naltrexone administration on the second day of detoxification treatment. The patients were divided into two groups following DSM-IV criteria for ASPD. Group A comprised 14 ASPD patients and group B comprised 18 patients without ASPD. Slight and transient withdrawal symptoms and mood changes were demonstrated on the second day in the whole sample of patients, in association with a significant, but moderate, elevation of heart rate, blood pressure, NE (two-fold), EPI (five-fold), ACTH (two-fold) and CORT (two-fold) plasma levels, in response to opioid receptor-antagonist administration. When evaluated separately in ASPD (group A) and non-ASPD patients (group B), significantly higher withdrawal symptoms and mood changes, heart rate, blood pressure, NE, ACTH and cortisol levels were observed in ASPD subjects. By contrast, no differences were found in EPI responses to naloxone-naltrexone administration between group A and B patients. The significant differences demonstrated in clinical and neuroendocrine responses to opioid receptor-antagonist administration, in relation to personality traits, could be due to reduced alpha-adrenergic receptor sensitivity, which was previously reported in ASPD, with a possible impairment of clonidine action. Our study suggests that a detailed diagnostic assessment before detoxification procedure may help to predict treatment outcome.